Continuous casting method



Feb. 10, 1970 R. F.VREIHMAN 9 CONTINUOUS CASTING METHOD Original FiledOct. 6, 1965 s Sheets-Sheet 1 INVENTOR Ric/9am 1- Pei/mum 3 Sheets-Sheet2 Original Filed Oct. 6, 1965 INVENTOR Feb. 10, 1970 R. F. REIHMANCONTINUOUS CASTING METHOD 3 Sheets-Sheet 5 Original Filed Oct. 6, 1965INVENTOR Richard E rPei/rman United States Patent 3,494,411 CONTINUOUSCASTING METHOD Richard F. Reihman, Quakertown, Pa., assignor toBethlehem Steel Corporation, a corporation of Delaware Originalapplication Oct. 6, 1965, Ser. No. 493,373, now Patent No. 3,421,572,dated Jan 14, 1969. Divided and this application Sept. 30, 1968, Ser.No. 763,714

Int. Cl. B22d 11/06 U.S. Cl. 164-83 6 Claims ABSTRACT OF THE DISCLOSUREAn apparatus and method for applying compressive and shear forces to thesurfaces of a continuous casting in an open-ended continuous castingmold. Selected portions of the mold are reciprocated toward and awayfrom each other in a transverse direction at a predetermined cyclic ratewhile the entire mold is reciprocated independently and at a differentcyclic rate in a longitudinal direction.

CROSS REFERENCES TO RELATED APPLICATIONS This application is a divisionof application Ser. No. 493,373, filed Oct. 6, 1965 now United StatesLetters Patent No. 3,421,572, issued Jan. 14, 1969.

BACKGROUND OF THE INVENTION This invention relates to the continuouscasting of metals and metal alloys and more particularly to an improvedmold assembly and an improved method of moving a mold assembly incontinuous casting apparatus.

Heretofore, many different types of apparatus and methods have beentried in order to cast molten metals and alloys in a single elongatedcasting rather than in a number of individual castings or ingots. Atfirst, various forms of an open-ended stationary mold were tried. Themajor difficulty with such a mold was that the solidified metal castingtended to stick to the walls of the mold making the withdrawal of thecasting from the mold difficult. This practice was also very slow andusually resulted in castings of poor surface quality. It was thensuggested to reciprocate an open-ended mold in a direction parallel tothe longitudinal axis of the casting, such as shown by U.S. Patent No.1,385,595 to Van Ranst. This practice not only reduced the frictionbetween the mold walls and the casting but also permitted casting at asomewhat faster rate with improved surface quality.

It has also been suggested to use a vertically split open-ended mold inwhich the mold sections are vibrated at right angles to the longitudinalaxis of the casting or oscillate about fixed points while keeping themold stationary in a vertical direction. Generally, this practice wasonly suitable for casting at relatively slow rates.

SUMMARY OF THE INVENTION It is therefore an object of my invention toprovide continuous casting apparatus and a method of operatingcontinuous casting apparatus which will enable one to cast molten metaland metal alloys at a relatively high rate of speed.

It is a further object of my invention to provide continuous castingapparatus and a method of using continuous casting apparatus which willproduce metal castings having superior surface quality.

It is a still further object of my invention to provide an open-endedmold assembly for the continuous casting of metals and metal alloyswhich greatly reduces any tendency of the solidified metal casting tostick to the walls of the mold during the casting operation.

I have discovered the foregoing objects can be at- 3,494,411 PatentedFeb. 10, 1970 ICC tained by using a longitudinally split open-endedwatercooled mold which is reciprocated in a longitudinal direction whileopposed sections of the mold are reciprocated toward and away from eachother in a transverse direction simultaneously with but independent ofthe reciprocation of the mold in the longitudinal direction.

BRIEF DESCRIPTION OF THE DRAWINGS Referring to the drawings whichillustrate an embodiment of my invention.

FIGURE 1 is a side elevation, partly in section, of continuous castingapparatus embodying my invention.

FIGURE 2 is a sectional view taken along line 2--2 of FIGURE 1.

FIGURE 3 is a top view, partly in section, of the mold assembly.

FIGURE 4 is a sectional view of the mold assembly taken along line 4-4of FIGURE 3.

DETAILED DESCRIPTION As shown in FIGURE 1, vertical structural columns 1support a horizontal working platform 2 above the level of the shopfloor 3. Rigidly attached to the working platform 2 is a rectangularstructural frame 4 comprised of vertical structural columns 5 andhorizontal girders 6. Structural frame 4 supports a tundish 7, a moldhousing 8 and the various drive means required to reciprocate the moldhousing 8 and the mold 9.

Molten metal from a ladle or holding furnace (not shown) is poured intotundish 7 from which the molten metal is then introduced into the top ofan elongated cavity of an open-ended, water-cooled, mold 9, where themolten metal is cooled until an elongated metal casting 10 having asolid exterior and a molten interior is formed. The partially solidifiedcasting 10 is withdrawn from the bottom of the mold cavity and is guidedinto a cooling chamber 11 where high pressure jets of water 12 spray thesurface of the casting 10, cooling it further. Opposed pairs of guiderolls 13 contact the sides of the casting and guide the casting throughthe cooling chamber 11. Immediately below the cooling chamber 11 is oneor more pairs of driven pinch rolls 14 which control the speed ofwithdrawal of the casting. The casting 10 is then either deflected to ahorizontal direction or, as shown in FIGURE 1, descends vertically tothe shop floor 3 where it is cut off into suitable lengths by cuttingtorches or the like (not shown).

As best illustrated in FIGURES l and 2, the mold housing 8 is suspendedwithin the rectangular structural frame 4 by trunnions 16. The trunnionsare attached to a pair of parallel arms 17 journaled at one end to theend of a shaft 18 attached to columns 5 of structural frame 4. The otherends of arms 17 are joined by a cross-member 19. The arms 17 are therebyfree to pivot about shaft 18 in parallel vertical planes. Directly underthe midpoint of cross member 19 are a hydraulic piston and cylinder 20connected to a hydraulic pump and valve arrangement, not shown. It willbe evident that raising and lowering of the piston in hydraulic cylinder20 will cause arms 17 to pivot about shaft 18 and in turn reciprocatemold housing 8 in a longitudinal direction parallel to the longitudinalaxis of the casting 10. This results in a shearing force parallel to thelongitudinal axis of the casting being applied to the surface of thecasting 10.

As shown in FIGURES 3 and 4, the mold 9 is set within the mold housing 8and has its side walls split longitudinally along lines parallel to thelongitudinal axis of the casting into pairs of opposed wall sections 21.Sections 21 are hollow and water-cooled and preferably made of copper.While I have illustrated the mold 9 in FIGURE 3 as comprised of fourwall sections of equal size for casting a square billet, it is apparentthat the mold 9 may be comprised of any even number of sections of anyrequired dimension.

Each mold section 21 is attached to the mold housing 8 by flexiblesupport members 22 attached both to the top and bottom of the rear facesof wall sections 21 as shown in FIGURE 4.

Also set within the mold housing 8 but surrounding the mold 9 ismechanical means for reciprocating a pair or pairs of opposed wallsections 21 toward and away from each other in a transverse directionsimultaneously with but independent of the reciprocation of the mold 9and mold housing 8 in the longitudinal direction.

This mechanical means includes for each wall section of the pair, adrive shaft 23 journaled on the mold housing 8 by suitable bearings 24,an eccentric 25 mounted on each of the drive shafts 23 and a connectingrod 35 connecting the eccentric 25 to the rear face of the respectivewall section 21 approximately midway between the top and bottom flexiblesupport members 22. As seen best in FIGURE 3 the drive shafts 23 all liein a common plane which is perpendicular to the longitudinal axis ofcasting 10. Drive shafts 23 are joined to one another by bevel gears 26positioned at the corners of mold housing 8 and are driven at the samespeed by shaft 27 driven by electric motor 28 through a jackshaft 29,sheaves 30 and flexible belts 31. Enough slack is maintained in theflexible belts 31 to permit the longitudinal reciprocation of the moldhousing 8.

The eccentrics 25 convert the rotary motion of drive shafts 23 into arectilinear motion in a direction transverse to the longitudinal axis ofthe casting. This motion is imparted to the wall sections 21 whichresults in a progressively increasing and then decreasing compressiveforce being applied to the casting perpendicular to the longitudinalaxis of the casting. Eccentrics 25 can be designed with a suitable dwelltime so that the compressive force is held at a maximum for apredetermined period of time against the surface of the casting beforethe force begins to decrease.

With the arrangement of wall sections 21 as shown in FIGURE 3, I preferto so position the eccentrics on drive shafts 23 so that as one pair ofopposed walls sections 21 are moving towards each other and against thecasting in the transverse direction, the other pair of opposed wallsections 21 are moving away from each other and the casting also in thetransverse direction. For casting large rectangular slabs, it may bepreferable for the wall sections 21 defining the narrow ends of the slabto move not at all. This may be done by replacing the respectiveeccentrics with circular bushings or by removing the respectiveconnecting rods 35.

As a result of the apparatus and methods of my invention, it is possibleto continuously cast metal castings of superior surface quality at rateshigher than has heretofore been possible.

As an example of my invention I have designed apparatus for casting a 2"x 2" square billet in which the mold is reciprocated in the longitudinaldirection at a cyclic rate of less than 300 cycles per minute with theupstroke being at a speed at least twice as fast as the downstroke. Thelength of the longitudinal stroke is between and 1 /2". The opposed wallsections are reciprocated toward and away from each other in thetransverse direction at a cyclic rate of 300-1700 cycles per minute andpreferably at a cyclic rate approximately twice that of the longitudinalreciprocation. The length of the stroke in the transverse direction is0.020 inch.

As many possible embodiments may be made of my invention withoutdeparting from the scope thereof, it is to be understood that all matterset forth or shown in the accompanying drawings is to be interpreted asillustrative and not in a limiting sense.

I claim:

1. A method of producing an elongated metal casting comprising:

(a) introducing molten metal into an elongated cavity in an open-endedwater-cooled mold,

(b) cooling the molten metal within said cavity until an elongated metalcasting having a solid exterior and a molten interior has been formed,

(c) reciprocating said mold in a longitudinal direction substantiallyparallel to the longitudinal axis of said casting,

(d) moving opposed sections of said mold toward and away from each otheragainst said casting in a transverse direction simultaneously with butindependent of the reciprocation of said mold in the longitudinaldirection,

(e) withdrawing said elongated metal casting from the bottom of saidmold, and

(f) cooling said casting until the interior thereof is completely solid.

2. A method of producing an elongated metal casting comprising:

(a) introducing molten metal into an elongated cavity in an open-endedwater-cooled mold,

(b) cooling the molten metal within said cavity until an elongated metalcasting having a solid exterior and a molten interior has been formed,

(c) reciprocating said mold in a longitudinal direction substantiallyparallel to the longitudinal axis of said casting,

(d) moving one pair of opposed sections of said mold toward each otheragainst said casting while moving a second pair of opposed sections ofsaid mold away from each other and said casting, said movementsoccurring in a transverse direction simultaneously with but independentof the reciprocation of said mold in the longitudinal direction.

3. The method of claim 2 wherein the reciprocation in the longitudinaldirection is at a different cyclic rate than the reciprocation of themold sections in the transverse direction.

4. A method of producing an elongated metal casting comprising:

(a) introducing molten metal into an elongated cavity in an open-endedwater-cooled mold,

(b) cooling the molten metal within said cavity until an elongated metalcasting having a solid exterior and a molten interior has been formed,

(0) applying a shearing force parallel to the longitudinal axis of saidcasting to the surface of said casting,

(d) simultaneously but independently applying a progressively increasingand then decreasing compressive force perpendicular to the longitudinalaxis of said casting to opposed surfaces of that portion of said castingcontained within said mold,

(e) withdrawing said elongated metal casting from the bottom of saidmold, and

(f) cooling said casting until the interior thereof is solid.

5. The method of claim 4 wherein the compressive force is held at amaximum for a predetermined length of time before decreasing said force.

6. The method of claim 4 wherein the shearing force is applied first inone direction and then in the opposite direction.

References Cited UNITED STATES PATENTS 2,698,978 1/1955 Welblund 164-832,818,616 1/1958 Rossi 164260 3,075,264 1/ 1963 Wognum 164-260 X FOREIGNPATENTS 1,404,087 5/ 1965 France.

102,995 11/1941 Sweden.

I. SPENCER OVERHOLSER, Primary Examiner R. S. ANNEAR, Assistant Examiner

